This application claims priority to Japanese patent application number 2001-091611 filed Mar. 28, 2001.
1. Field of the Invention
This invention relates to a structure for mounting a motor for moving a lens barrel of a camera along a direction of an optical axis of a lens in accordance with a variable power operation.
2. Description of the Related Art
In cases where photographing operations with cameras are performed, variable power operations (zooming operations) are often performed for altering a focal length of a taking lens between a wide angle photographing side and a telescopic photographing side. For the variable power operations, a lens barrel of the camera is moved along the direction of the optical axis of the lens. At this time, ordinarily, the lens barrel is driven by a motor via a gear train comprising a plurality of spur gears. The motor has an output shaft, to which a spur gear has been secured, and the gear train comprising the spur gears is utilized. Therefore, the motor is located inevitably such that the output shaft is parallel with the optical axis direction. The motor is secured by mounting screws, and the like, to a motor securing member and is thereby secured to a frame body of the camera.
In cases where the output shaft of the motor is to be located in parallel with the optical axis direction, if the motor is an ordinary motor having an approximately circular cylinder-like shape, a comparatively large space for accommodating the entire length of the motor within a frame body of the camera will be required of the camera along the length direction of the motor, i.e. along the optical axis direction. Therefore, in such cases, the problems occur in that the camera cannot be rendered thin.
In order for the problems described above to be solved, it may be considered to employ a technique, wherein the output shaft of the motor is located in a plane normal to the optical axis (i.e., at a right angle with respect to the thickness direction of the camera). However, with the technique described above, in cases where the motor is secured by screws to the frame body, threaded holes for engaging with the screws also extend in the direction normal to shafts (i.e., rotation shafts) of the spur gears of the gear train, which shafts are secured to the frame body and are parallel with the optical axis. Therefore, due to the locations of the shafts of the spur gears of the gear train, the problems occur in that the shafts of the spur gears of the gear train obstruct the motor securing work, and the motor cannot be secured easily to the frame body. Also, when a tool for screwing is inserted toward a motor securing section, the problems occur in that the frame body is apt to obstruct the tool insertion path. Further, instead of the motor being mounted with the screwing process, it may be considered to mount the motor with a process for fitting the motor into the frame body. However, in cases where the motor is mounted with a process for fitting the motor into the frame body, the problems occur in that the motor cannot be mounted tightly, and looseness of the motor mounting is apt to occur with the passage of time.
The primary object of the present invention is to provide a motor mounting structure for a camera, which enables a camera to be rendered thin.
The present invention provides a motor mounting structure for a camera, the camera comprising:
i) a lens barrel associated with a frame body of the camera such that the lens barrel is capable of advancing and retracting along an optical axis direction,
ii) a film accommodating chamber, which is located on the side outward from the lens barrel with respect to a direction normal to the optical axis direction, and
iii) a motor, which is secured to the frame body, mechanical power of the motor being transmitted to the lens barrel via a gear train comprising a plurality of gears in order to move the lens barrel along the optical axis direction,
wherein the motor is located within a space, which is defined by the lens barrel and the film accommodating chamber, such that an output shaft of the motor extends in a plane normal to the optical axis direction, and
the frame body has a path, through which a tool for securing the motor to the frame body by screwing is to be inserted.
The term xe2x80x9cfilm accommodating chamberxe2x80x9d as used herein means the space for accommodating a film cartridge or the space for winding up and accommodating the film having been drawn out of the film cartridge.
In the motor mounting structure for a camera in accordance with the present invention, the output shaft of the motor extends in the plane normal to the optical axis direction. Specifically, the output shaft of the motor may extend in the plane intersecting exactly at an angle of 90xc2x0 with the optical axis direction. Alternatively, the output shaft of the motor may be inclined slightly with respect to the plane intersecting exactly at an angle of 90xc2x0 with the optical axis direction.
Also, in the motor mounting structure for a camera in accordance with the present invention, the path may be formed such that the tool inserted through the path does not interfere with rotation shafts of the gears constituting the gear train. The path may be formed by forming a cut-away area at a portion of the frame body.
The formation of the cut-away area includes the cases wherein the cut-away area is formed inwardly from an edge of the frame body, and the cases wherein a hole (an opening), which does not open to the edge, is formed in the frame body.
With the motor mounting structure for a camera in accordance with the present invention, the motor for moving the lens barrel via the gear train along the optical axis direction is located within the space, which is defined by the lens barrel and the film accommodating chamber, such that the output shaft of the motor extends in the plane normal to the optical axis direction. Also, the frame body has the path, through which the tool for securing the motor to the frame body by screwing is to be inserted. Therefore, the thickness of the camera need not be set to be large in the optical axis direction in order for the motor to be accommodated. Accordingly, the camera is capable of being rendered thin. The motor mounting structure for a camera in accordance with the present invention is particularly efficient for a small camera utilizing small film, such as an APS cartridge.
With the motor mounting structure for a camera in accordance with the present invention, the path may be formed such that the tool inserted through the path does not interfere with the rotation shafts of the gears constituting the gear train. In such cases, the path is capable of being formed reliably. In cases where the path is formed by forming the cut-away area at a portion of the frame body, the path is capable of being formed easily.